Horses do not have collarbones.
Their front limbs are directly attached to the spinal column by muscles, tendons and ligaments. The adaptation improves running efficiency because once the shoulder blade is no longer restrained by the clavicle, it can act almost like an extra limb segment. This results in a lengthened stride.
Horses do not have a gall bladder.
Horses don’t have a gallbladder because horses are designed to eat constantly as “trickle feeders.” The small amount of fat that they eat while grazing is easily managed by the liver. Therefore, there is no need to store bile — the gall bladder’s primary purpose — in large quantities.
Horses have the largest eyes of any land mammal.
The eyes of a horse are roughly 1.34 inches in diameter, surpassed only by the eyes of whales, seals and ostriches. This allows horses to see nearly every part of their body and all around them, especially since they can move their eyes in different directions at the same time.